Is there such a thing as too much Wi-Fi?

Ever gone into a store and looked up? You’d
be surprised what you can find hanging off the ceilings.

Like where I’m hanging out now—one of those
tiny mobile phone stores. It’s not a large space but there are three Wi-Fi APs
hanging off the ceiling in a retail space of about 400 sq. ft. (37 m²).
That’s roughly equal to one AP for every 133 sq. ft. (12 m²). 
Does such a small place really need three APs?

Is Three a Crowd?

People who study crowd density have rules
of thumb to estimate the number of people that can occupy a given space. A
loose crowd, where everyone is about an arm’s length from their neighbor,
requires roughly 10 square feet (1 square meter) per person.

At that density, you could pack forty people in this store. It would be uncomfortable and leave no room for shelves, tables, or check-out counters. Anyone who has shopped around a major holiday knows what it’s like to look inside a jam-packed retail store and say “Hard pass”.

Back to those APs blinking above me. Let’s
assume everyone here has a Wi-Fi-enabled smartphone. At our maximum crowd
capacity, that’s 40 devices, plus a few more if the store uses Wi-Fi for
point-of-sale (POS) devices. Let’s round up to 60.

You might think to yourself, “60 devices
divided by three APs is only 20 devices per AP. That’s great!” Except most APs
have dual radios. The actual number will be 10 devices per radio.

I can hear you now. You’re probably the
person behind me in the check-out line wondering why this woman is muttering to
herself about APs. “Isn’t fewer devices per radio better?” you’d say.

Maaaybe.

First, is everyone really going to be using
all of those devices at the same time? The answer is almost certainly no. Let’s
assume 50% of these devices are actively used at any given time for email, web
surfing,  cat videos, writing blogs, and so on. Everyone else is shopping,
paying at …